Techniques for cooling a set of circuit boards within a rack mount cabinet

ABSTRACT

A data storage subsystem is configured to mount within a rack mount cabinet. The data storage subsystem includes a housing configured to mount to a set of vertical rails of the rack mount cabinet, a set of circuit boards configured to install in a vertically aligned manner within the housing to define a set of vertically oriented channels within a central space defined by the set of vertical rails of the rack mount cabinet, and a fan assembly configured to mount to the set of vertical rails in a position above the housing to generate a vertical air stream through the set of vertically oriented channels and to exhaust the vertical air stream to an external location above the rack mount cabinet. The vertical air stream enables robust heat removal from the set of circuit boards even if the rack mount cabinet does not reside in a cold-isle environment.

CROSS REFERENCE TO RELATED APPLICATIONS

This Patent Application is a Divisional of U.S. patent application Ser.No. 10/658,695 filed on Sep. 9, 2003 now U.S. Pat. No. 6,987,673,entitled, “TECHNIQUES FOR COOLING A SET OF CIRCUIT BOARDS WITHIN A RACKMOUNT CABINET”, the contents and teachings of which are herebyincorporated by reference in their entirety.

BACKGROUND OF THE INVENTION

A typical electronic equipment cabinet includes a frame and a set ofpanels. The frame supports electronic equipment (e.g., power supplies,backup batteries, backplanes, circuit boards, etc.). The set of panels(e.g., doors, side panels, top panels, etc.) controls access to theelectronic equipment supported by the frame (e.g., protects theequipment against damage, encloses the equipment to enable fans togenerate an air stream to cool the equipment, etc.).

One conventional electronic equipment cabinet (hereinafter referred toas the “conventional rack mount cabinet”) includes an assembly of rigidhorizontal and vertical metal beams that are fastened together to form astandard-sized frame. In particular, the metal beam assembly defines astandard width dimension for the cabinet (e.g., 19-inches) as well asdefines uniformly-spaced, standard height attachment points (e.g., astandard 40-U rack) to enable vertical stacking of modularized equipmentalong the attachment points. Accordingly, such a cabinet enablesequipment manufacturers to manufacture equipment as modularizedcomponents in common sizes (e.g., a standard-sized rack mount disk drivesubsystem, a standard-sized rack mount power supply subsystem, etc.) forvertical integration with other modularized components within the rackmount cabinet.

Each modularized component typically includes, among other things, (i) acomponent chassis which mounts to the metal beams forming thestandard-sized frame, (ii) circuitry which fastens to that componentchassis, and (iii) a cooling subsystem. Users can then verticallycombine modularized components from different manufacturers in amix-and-match fashion within the rack mount cabinet to form an overallsystem (e.g., a data storage system, a network system, a general purposecomputer system, etc.). To allow for such mixing and matching, for eachmodularized component, the manufacturer typically designs a separate andindependent cooling subsystem to provide horizontal air flow from thefront of the cabinet to the back of the cabinet through the chassis andacross the circuitry of that modularized component to remove heat fromthat circuitry during operation.

For such a rack mount cabinet, the cooling subsystems of the rack mountmodularized components work simultaneously to adequately cool thecircuitry of the rack mount components when the rack mount cabinetresides adjacent an isle of cold air, i.e., a so-called “cold isle”location in which the cooling subsystems (i) draw air from an isle ofcold air where system operators (e.g., technicians) typically reside and(ii) exhaust that air to an isle of higher temperature air at the backof the rack mount cabinet. The air at the back of the rack mount cabinetis warmer than that of the cold isle since it has absorbed heat as itpassed horizontally through the cabinet and past the circuitry of therack mount components in order to cool that circuitry. To facilitatesuch cooling, panels of the rack mount cabinet typically reside alongthe sides, tops and bottoms of the frame thus preventing air fromescaping as it flows horizontally through the rack mount cabinet.

Another conventional electronic equipment cabinet (hereinafter referredto as the “conventional monolithic cabinet”) includes a custom-builtframe that defines customized dimensions at different locations ratherthan uniform dimensions as in the conventional rack mount cabinet. Here,a single manufacturer has control over the entire design of the cabinetand its circuits. In particular, the manufacturer has the luxury ofbeing able to set the customized dimensions so that individualcomponents operate together in an efficient manner. For example, themanufacturer typically includes a single cooling subsystem for coolingall of the circuits within the entire cabinet to minimize costs forcooling the equipment. In one system that uses a conventional monolithiccabinet, the cooling subsystem resides at the top of the cabinet to drawair vertically through the custom-built frame and force the air out thetop of the custom-built frame.

SUMMARY

Unfortunately, there are deficiencies to the above-describedconventional electronic equipment cabinets. For example, in connectionwith the above-described conventional rack mount cabinet that uses rackmount components with separate and individual horizontal air flowcooling subsystems, the cooling subsystems of the components areeffective in “cold isle” locations, but loose their effectiveness inother locations that do not provide access to a reservoir of cold air atthe front of the rack mount cabinet. In particular, even though hot airtends to rise vertically, such cooling subsystems attempt to direct airlaterally in a direction that is substantially perpendicular to thevertical direction. If these cooling subsystems are unable to adequatelycool the circuitry of the rack mount components, the circuitry of suchcomponents may operate improperly or in extreme cases sustain damage dueto overheating. Such a deficiency will become more pronounced ascircuitry evolves and higher-power integrated circuit devices (ICs) withgreater cooling requirements become more common.

Additionally, in connection with the above-described conventionalmonolithic cabinet that uses a custom-built frame, the electroniccircuits for such a cabinet are typically unsuitable for use in astandard-sized rack mount cabinet. In particular, the electroniccircuits do not fit within a common-sized cabinet. Accordingly, amanufacturer of such electronic circuits is unable to sell theelectronic circuits in higher volume to reduce manufacturing costs,e.g., the manufacturer cannot sell the equipment to a market which islooking to mix-and-match rack mount components vertically within acommon-sized cabinet.

In contrast to the above-described conventional electronic cabinets,embodiments of the invention are directed to techniques for mounting adata storage subsystem within a rack mount cabinet where the datastorage subsystem has a fan assembly configured to generate a verticalair stream through at least a portion of the rack mount cabinet and toexhaust the vertical air stream to an external location above the rackmount cabinet. Such techniques enable manufacturers of the data storagesubsystem to provide effective cooling to circuitry of the data storagesubsystem (e.g., adequate cooling even in non-cold isle locations) aswell to broaden the market for the data storage subsystem to the rackmount cabinet market (e.g., a market in which customers are looking tomix-and-match rack mount components within common-sized cabinets).

One embodiment of the invention is directed to a data storage subsystemfor mounting within a rack mount cabinet. The data storage subsystemincludes a housing configured to mount to a set of vertical rails of therack mount cabinet, a set of circuit boards configured to install in avertically aligned manner within the housing to define a set ofvertically oriented channels within a central space defined by the setof vertical rails of the rack mount cabinet, and a fan assemblyconfigured to mount to the set of vertical rails in a position above thehousing to generate a vertical air stream through the set of verticallyoriented channels and to exhaust the vertical air stream to an externallocation above the rack mount cabinet. The vertical air stream enablesreliable and robust heat removal from the set of circuit boards even ifthe rack mount cabinet does not reside in a cold-isle environment.Additionally, use of the rack mount cabinet to mount the housing of thedata storage subsystem enables mixing-and-matching of components fromdifferent manufacturers thus broadening the market for the data storagesubsystem (e.g., enabling the data storage subsystem to be verticallystacked with other components by a common-sized frame).

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other objects, features and advantages of theinvention will be apparent from the following description of particularembodiments of the invention, as illustrated in the accompanyingdrawings in which like reference characters refer to the same partsthroughout the different views. The drawings are not necessarily toscale, emphasis instead being placed upon illustrating the principles ofthe invention.

FIG. 1 is a block diagram of a rack mount data storage system which issuitable for use by the invention.

FIG. 2 is a perspective view of a rack mount cabinet of the rack mountdata storage system of FIG. 1.

FIG. 3 is a perspective view of the rack mount cabinet of the rack mountdata storage system when a set of front panels of the cabinet isremoved.

FIG. 4 is a perspective view of a housing of the rack mount data storagesubsystem of FIG. 1.

FIG. 5 is a flowchart of a procedure which is performed by amanufacturer when making the rack mount data storage system of FIG. 1.

FIG. 6 is a block diagram of a rack mount data storage system having analternative air intake configuration which is suitable for use by theinvention.

DETAILED DESCRIPTION

Embodiments of the invention are directed to techniques for mounting adata storage subsystem within a rack mount cabinet where the datastorage subsystem has a fan assembly configured to generate a verticalair stream through at least a portion of the rack mount cabinet and toexhaust the vertical air stream to an external location above the rackmount cabinet. Such techniques enable an equipment manufacturer toprovide effective cooling of circuitry of the data storage subsystem(e.g., adequate cooling even in non-cold isle locations) as well tobroaden the market for the data storage subsystem to the rack mountcabinet market (e.g., a market in which customers are looking tomix-and-match rack mount components vertically within common-sized rackmount cabinets).

FIG. 1 shows a rack mount data storage system 20 which is suitable foruse by the invention. The rack mount data storage system 20 includes arack mount cabinet 22, a power supply subsystem 24, a disk drivesubsystem 26 and a data storage circuitry subsystem 28. The rack mountcabinet 22 includes a frame 30 that defines a central space 32 withinwhich resides the power supply subsystem 24, the disk drive subsystem 26and the data storage circuitry subsystem 28. In particular, the powersupply subsystem 24, the disk drive subsystem 26, and the data storagecircuitry subsystem 28 are vertically stacked and integrated within theframe 30.

As shown in FIG. 1, the power supply subsystem 24 is configured to forma substantially horizontal air stream 36 that travels from a front 38 ofthe cabinet 22 to a back or rear 40 of the cabinet 22 past power supplycircuitry contained therein (e.g., multiple power supplies) to cool thatpower supply circuitry. Similarly, the disk drive subsystem 26 isconfigured to form a substantially horizontal air stream 42 from thefront 38 of the cabinet 22 to the back 40 of the cabinet 22 past diskdrive circuitry contained therein (e.g., an array of disk drives forhigh capacity non-volatile data storage) to cool that disk drivecircuitry. These horizontal air streams 36, 42 are well-suited forrespectively removing heat from the power supply subsystem 24 and thedisk drive subsystem 26 since the circuitry of such subsystems 24, 26tends not to include temperature-critical components (e.g., high powerintegrated circuit devices).

As further shown in FIG. 1, the data storage circuitry subsystem 28includes a housing 44, a fan assembly 46, a duct 48, a backplane 50, afirst set of circuit boards 52 and a second set of circuit boards 54.The housing 44 is configured to mount to the rack mount cabinet 22within a portion 56 of the central space 32 that is above the powersupply subsystem 24 and also above the disk drive subsystem 26. The fanassembly 46 is disposed at the top of the housing 44, and the duct 48 isdisposed at the bottom of the housing 44. The backplane 50 mounts withinthe housing 44 and resides in a substantially vertical orientationrelative to the cabinet 22. The circuit boards 52, 54 individuallyinsert into the housing 44 where they reside in substantially verticalorientations relative to the cabinet 22.

In one arrangement, the backplane 50 of the data storage circuitrysubsystem 28 includes connectors on both sides. That is the backplane 50is a rigid planar member having a first set of connectors on a frontsurface and a second set of connectors on a back surface to provide highdensity connections. In this arrangement, the first set of circuitboards 52 is configured to slide in a first direction 58 into thehousing 44 (e.g., into slots of a card cage portion of the housing 44)and connect in a substantially perpendicular manner to the backplane 50through the front 38 of the cabinet 22. Similarly, the second set ofcircuit boards 54 is configured to slide in a second direction 60 intothe housing 44 and connect to the backplane through the back 40 of thecabinet 22. As shown in FIG. 1, the second direction 60 is substantiallyopposite the first direction 58.

It should be understood that the above-illustrated midplane/backplane 50allows for enhanced performance and reliability. For example, themidplane/backplane 50 can be configured to provide a high-density set ofrelatively short-latency connections between the circuit boards 52, 54for robust connectivity. Additionally, vertical airflow (see the arrows62) is optimal and alleviates the need for any air holes within thebackplane 50 itself. Without the vertical air stream 62, the backplane50 would need to provide air holes for horizontal (e.g., front-to-rear)airflow thus leaving less area for signal traces and thus increasing theboard pitch for such traces. However, use of the vertical air stream 62relative to the backplane 50 and the circuit boards 52, 54 enableshigher air speed (less area) and more convective cooling across theboard components. Such use also forces more air onto the board surfaceand boundary layer of the components for better heat transfer. Thisallows for higher wattage/performance components to be used on thecircuit boards 52, 54 (and perhaps the backplane 50 as well) and enableseffective lowering of the operating temperatures for increasedreliability. Furthermore, by eliminating the need for air holes, thevertical air stream 62 enables the backplane 50 to provide more signalcapability and lowers the cost of the midplane/backplane 50.

In one arrangement, the front-installation circuit boards 52 areconfigured to perform data storage system operations on a set of diskdrives of the disk drive subsystem 26 on behalf of a set of externalhosts. In this arrangement, the rear-installation circuit boards 54 areconfigured to operate as an interface between the front-installationcircuit boards 52 and the set of external hosts.

During operation, the data storage circuitry subsystem 28 receives powerfrom the power supply subsystem 24 and accesses data within the diskdrive subsystem 26 on behalf of one or more hosts (e.g., externalclients). To this end, the backplane 50 and the circuit boards 52, 54perform high speed data storage operations (e.g., write operations, readoperations, data caching operations, data pre-fetching operations,etc.), and the fan assembly 46 generates an air stream 62 through theportion 56 of the central space 32 to remove heat from the circuitboards 52, 54. In particular, the fan assembly 46 draws air from thefront 38 of the cabinet 22 through the housing 44 to cool circuitry 64,66 (e.g., high speed ICs) of the circuit boards 52, 54. As mentionedearlier, the backplane 50 divides the portion 56 of the central spaceinto two portions, i.e., two passageways or airways for air flow.Accordingly, as the air enters the intake duct 48, a portion 62-A of theair stream 62 passes in front of the backplane 50 to cool the circuitboards 52 and a separate portion 62-B of the air stream 62-B passes inback of the backplane 50 to cool the circuit boards 54.

The location of the fan assembly 46 at the top of the cabinet 22 reducesthe sound level to the user and enables easy removal without having toremove other components (e.g., cables, etc.) for access. In onearrangement, when the cabinet 22 has a sufficient opening at the top,the fan assembly 46 exhausts the air of the air stream 62 to a location67 above the cabinet 22. In an alternative arrangement, when the cabinet22 does not have a sufficient opening at the top, the fan assembly 46exhausts the air of the air stream 62 out the back 40 of the cabinet 22at a location 68 which is substantially higher than the bottom of thehousing 44 (e.g., two to three feet higher than the bottom of thehousing 44, at a location adjacent the top of the cabinet 22, etc.). Inthis alternative arrangement, an optional/removable deflector plate 69(shown as a dashed line 69 at the top of the fan assembly 46) steers thevertical air stream 62 back to the horizontal direction (see arrow 70)so that it exhausts into the location 68.

For either arrangement, the duct 48 deflects air of the air stream 62from a substantially horizontal flow (see arrows 72) to a substantiallyvertical flow (see arrows 62) through the portion 56 of the centralspace 32 to robustly carry heat away from the circuitry 64, 66 of thecircuit boards 52, 54. Accordingly, both of these arrangements are verywell-suited for temperature-critical circuitry (e.g., high-speed andhotter-running integrated circuits, higher density circuits, circuitrythat must run in a narrower temperature margin, etc.) even if thecabinet 22 does not reside in a cold isle location. That is, thevertically oriented air stream 62 leverages of the tendency for heat torise thus more effectively drawing heat away from such circuitry (e.g.,high-speed processors and application specific integrated circuitdevices) and maintaining a stable operating environment for suchcircuitry. Furthermore, the vertically oriented air stream 62 alleviatesthe need to provide holes within the backplane 50 for horizontalairflow. Such operation is superior to the earlier-describedconventional modularized rack mount components in which horizontal airstreams attempt to move heated air transversely and struggle, andperhaps fail to adequately cool high power circuits when such componentsdo not reside in a cold isle location.

It should be understood that the circuits of the power supply subsystem24 and the data storage subsystem 26 are not as temperature-sensitive asthe circuitry 64, 66 of the circuit boards 52, 54. Accordingly, duringoperation, the circuitry of the power supply subsystem 24 (i.e., a setof power supplies, a fan subassembly, etc.) is adequately cooled by thesubstantially horizontal air stream 36 passing therethrough. Inparticular, the air stream 36 sufficiently removes heat from the powersupply subsystem 24 even if the cabinet 22 does not reside in a coldisle location since that circuitry is not very temperature-sensitivevis-á-vis high power, hot-running IC circuit board devices. Similarly,the circuitry of the data storage circuitry subsystem 26 is adequatelycooled by the substantially horizontal air stream 42 passingtherethrough even if the cabinet 22 does not reside in a cold islelocation. Further details of the invention will now be provided withreference to FIG. 2.

FIG. 2 shows a perspective view of the cabinet 22 of the rack mount datastorage system 20. As shown in FIG. 2, the rack mount data storagesystem 20 further includes panels 80 which control access to the variousoperating components of the rack mount data storage system 20. Thepanels 80 includes a pair of side panels 82-A, 82-B (collectively, sidepanels 82), a set of front panels 84 (e.g., a set of front doors)disposed at the front 38 of the cabinet 22, and a set of rear panels 86(e.g., a set of rear doors, generally depicted by the arrow 86) disposedat the rear 40 of the cabinet 22. The panels 80 attach to the frame 30of the cabinet 22, and operate to control access to the central space 32(also see FIG. 1). In particular, the panels 80 protect equipment housedwithin the central space 32 of the rack mount cabinet 22 against damage,and enclose that equipment to enable fans to generate air flow to coolthe equipment.

As shown in FIG. 2, the set of front panels 84 defines apertures 88 thatpermit air to enter the central space 32. In particular, the air flowsin a substantially horizontal direction (see the arrow 72) to removeheat from the various vertically stacked components of the rack mountdata storage system 20. As explained earlier, the power supply subsystem24 and the disk drive subsystem 26 undergo cooling via substantiallyhorizontal air flows. In contrast, the data storage circuitry subsystem28 undergoes cooling by way of a substantially vertical air stream 62.To this end, as air enters the duct 48 of the data storage circuitrysubsystem 28 (also see FIG. 1), the walls of the duct 48, in combinationwith surfaces defined by other elements (e.g., the backplane 50, thecircuit boards 52, 54, etc.), deflects the air from the lateraldirection into a substantially vertical direction (see the arrows 62)for more effective cooling.

In one arrangement, the air of the air stream 62 exits verticallythrough an opening 90 at the top of the cabinet 22 thus exhausting intoa location 48 over the cabinet 22. In an alternative arrangement, theair of the air stream 62 exits horizontally (e.g., see the arrow 70) toa location 68 at the back of the cabinet 22 which is substantiallyhigher than the apertures 88 through which the air entered (e.g., theair exits out at a location that is two or three feet higher than theheight in which is entered). Further details of the invention will nowbe provided with reference to FIG. 3.

FIG. 3 is a perspective view of the rack mount data storage subsystem 20with the set of front panels 84 (FIG. 2) removed to illustrate variouscomponents within the rack mount cabinet 22. In particular, FIG. 3 showsthe frame 30 of the cabinet 22, and the data storage circuitry subsystem28 mounted to the frame 30. The frame 30 includes a set of verticalrails 100 defining the central space 32 (e.g., a vertical rail 100 ineach corner of the cabinet 22 to define the central space 32therebetween). The set of vertical rails 100 defines mounting holes 102that enable the power supply subsystem 24 (not shown in FIG. 3 but shownin FIG. 1), the disk drive subsystem 26 (not shown in FIG. 3 but shownin FIG. 1) and the data storage circuitry subsystem 28 to mount atstandard intervals in a vertically integrated fashion (e.g., themounting holes 102 of each vertical rail 100 defines holes at standardU-intervals).

As shown in FIG. 3, the housing 44 of the data storage circuitrysubsystem 28 mounts to a top portion 104 of the set of vertical rails100. Accordingly, when the power supply subsystem 24, the disk drivesubsystem 26 and the data storage circuitry subsystem 28 are verticallystacked within the cabinet 22, the data storage circuitry subsystem 28is above the other component subsystems 24, 26 (also see FIG. 1). As aresult, the fan assembly 46 of the data storage circuitry subsystem 28is capable of exhausting the vertical air stream 62 to an elevated areaabove the cabinet 22 (e.g., see the locations 48, 68 in FIGS. 1 and 2).Further details of the invention will now be provided with reference toFIG. 4.

FIG. 4 shows a perspective view of the data storage circuitry subsystem28 which is configured to mount to the rack mount frame 30 of thecabinet 22. As shown, the data storage circuitry subsystem 28 isessentially a self-contained unit that can be added to a standard rackmount cabinet, e.g., stacked and integrated within a generic or standardNEMA (National Engineers and Mechanics Association) rack. In onearrangement, when the data storage circuitry subsystem 28 is installedwithin the rack mount cabinet (e.g., see the portion 56 of the centralspace 32 of FIGS. 1 and 2), the housing 44 enables an air stream 62 toexhaust out the top (see FIG. 4). In another arrangement, the housing 44enables an air stream 62 to exhaust out the upper rear 68 of the housing44, e.g., using the optional deflector plate 69 (see FIG. 1).

As shown in FIG. 4, the circuit boards 52, 54 insert horizontally withinthe housing 44. Once the circuit boards 52, 54 are installed, theyreside in a vertically aligned manner to enable airflow in the verticaldirection (see the arrow 62 in FIG. 4). That is, when the circuit boards52, 54 are connected to the backplane 50, the circuit boards 52, 54define a set of vertically oriented channels 110. In particular, thecircuit boards 52 are vertically aligned and substantially parallel toeach other, and also are substantially perpendicular to the backplane 50to form the channels 110. Similarly (although not shown in FIG. 4), thecircuit boards 54 are substantially parallel to each other and aresubstantially perpendicular to the backplane 50 to form more channels110. In one arrangement, doors 112, 114 (shown generally as arrows 112,114 for simplicity) are installed at the front 116 and at the rear 118of the housing 44 to cover the channels 110 and thus prevent air of theair stream 62 from escaping as the air passes over the circuit boards52, 54. Accordingly, there is little or no leakage and the vertical airstream 62 reliably and robustly removes heat from the circuitry 64, 66(FIG. 1) of the circuit boards 52, 54.

As shown in FIG. 4, the duct 48 operates as an intake or plenum for air.By way of example only, the housing 44 further defines slots 120 tocarry a set of disk drive assemblies. The slots 120 reside below theintake duct 48 so that the disk drive assemblies do not substantiallyinterfere with air flow at the front 116 of the housing 44 into thevertically oriented channels 110.

As further shown in FIG. 4, the fan assembly 46 of the data storagecircuitry subsystem 28 includes a carrier portion (or simply carrier)122 and a set of fan subassemblies 124-A, 124-B, 124-C (collectively,fan subassemblies 124). The carrier 122 is essentially an extension of acard cage portion 126 of the housing 44. As explained earlier inconnection with FIG. 3, the housing 44 mounts to top portions 104 of theset of vertical rails 100 of the rack mount cabinet 22. Accordingly,each fan subassembly 124 directs the air stream 62 in a direction 62that is substantially parallel to the set of vertical rails 100 and intoan external location above the rack mount cabinet (also see locations 48and 68 in FIGS. 1 and 2).

Furthermore, as shown in FIG. 4, each fan subassembly 124 includesmultiple fans 126 disposed in a row. Accordingly, when all of the fansubassemblies 124 install within the carrier 22, the fans 126 reside inan N×M array (e.g., a 3-by-3 array of fans 126). N equals the number offan assemblies 124 in the carrier (e.g., three), and M equals the numberof fans 126 within each fan assembly 124 (e.g., three). It should beunderstood that other numbers for N and M are suitable for use by theinvention. In one arrangement, the number M of fans 126 in each fansubassembly 124 is greater than two, and the number N of fansubassemblies 124 is greater than two, as well.

It should be understood that each fan subassembly 124 is configured tooperate independently of the other fan subassemblies 124 to enable hotswapping of an individual fan subassembly 124 while other fanssubassemblies 124 remain in operation in response to the set of powersupply signals from the power supply subsystem 24. Additionally, itshould be understood that each fan subassembly 124 further includes astatus indicator 128 (e.g., a set of LEDs) to selectively indicateproper operation and improper operation of the multiple fans 126 of thatfan subassembly 124. Accordingly, if a fan 126 of a fan subassembly 124were to fail, a technician can easily detect that failure by examiningthe status indicator 128 of that fan subassembly 124 and hot swap thatfan subassembly 124 with a new fan subassembly 124 having new fans 126.Further details of the invention will now be provided with reference toFIG. 5.

FIG. 5 is a flowchart of a procedure 140 which is performed by amanufacturer when making the rack mount data storage system 20. In step142, the manufacturer mounts the power supply subsystem 24 and the diskdrive subsystem 26 to the rack mount cabinet 22. In particular, themanufacturer attaches the subsystems 24, 26 to the frame 30 in avertically stacked manner. Once the subsystems 24, 26 have been properlyinstalled, both the power supply subsystem 24 and the disk drivesubsystem 26 provide substantially horizontal air flow cooling throughthe cabinet 22.

In step 144, the manufacturer installs the data storage circuitrysubsystem 28 to the rack mount cabinet 22. In particular, themanufacturer mounts the data storage circuitry subsystem 28 so that itresides above both the power supply subsystem 24 and the disk drivesubsystem 26.

In step 146, the manufacturer attaches the fan assembly 46 to the rackmount cabinet. The fan assembly 46 resides above the data storagecircuitry 64, 66 of the data storage circuitry subsystem 28.Accordingly, the fan assembly 46 is capable of generating a vertical airstream 62 through the data storage circuitry 64, 66 (i.e., past thecircuit boards 52, 54) and exhausting the vertical air stream 62 to anexternal location above the rack mount cabinet 22 (see locations 48, 68in FIGS. 1 and 2).

It should be understood that the manufacturer is capable of performingsteps 142, 144, 146 in other orders as well. For example, themanufacturer can install the data storage circuitry 64, 66 prior toinstalling the power supply subsystem 24 and the disk drive subsystem26.

As mentioned above, embodiments of the invention are directed totechniques for mounting a data storage circuitry subsystem 28 within arack mount cabinet 22 where the data storage circuitry subsystem 28 hasa fan assembly 46 configured to generate a vertical air stream 62through at least a portion of the rack mount cabinet 22 and to exhaustthe vertical air stream 62 to an external location above the rack mountcabinet 22. Such techniques enable an equipment manufacturer to provideeffective cooling of circuitry of the data storage circuitry subsystem28 (e.g., adequate cooling even in non-cold isle locations) as well tobroaden the market for the data storage circuitry subsystem 28 to therack mount cabinet market (e.g., a market in which customers are lookingto mix-and-match rack mount components vertically within common-sizedcabinets).

While this invention has been particularly shown and described withreferences to preferred embodiments thereof, it will be understood bythose skilled in the art that various changes in form and details may bemade therein without departing from the spirit and scope of theinvention as defined by the appended claims.

For example, FIG. 6 shows an arrangement for the invention which issimilar to that of FIG. 1. However, in the arrangement of FIG. 6, theduct 48 intakes air from both the front 38 and the back 40 of thecabinet 22. Since the power supply subsystem 24 and the data storagesubsystem 26 exhaust air to the back 40 of the cabinet 22, air 150 atthe back 40 of the cabinet 22 is higher in temperature than that at thefront 38 of the cabinet 22. Nevertheless, the arrangement of FIG. 6 iswell-suited for certain situations. In particular, intaking of thepre-heated air 150 into the duct 48 can provide less impedance andhigher airflow. This lower impedance and higher airflow can provide moreeffective cooling of the circuitry 64, 66 than a lower airflow even ifthe lower airflow is at a somewhat lower temperature.

Additionally, it should be understood that the circuitry 64, 66 can havedifferent cooling requirements. In one arrangement, the circuitry 66 ofthe circuit boards 54 includes adapter circuits for communicating withexternal hosts, and the circuitry 64 of the circuit boards 52 includeshigher wattage control circuits (e.g., front-end and back-end directorcircuitry for a Symmetrix system by EMC Corporation of Hopkinton, Mass.)for performing data storage operations. In this arrangement, the fans126 (also see FIG. 4) within the fan assembly 46 are justified to thefront 38 of the cabinet 22. Accordingly, the fan assembly 46 provideshigher airflow across the circuit boards 52 (also see the arrow 62-A inFIG. 1) than across the circuit boards 54 (see the arrow 62-B in FIG. 1)since the circuit boards 52 generate more heat and require moreeffective cooling. In the arrangement where each fan subassembly 124includes three fans 126 (see FIG. 4), the rear fan 126 substantiallycontributes to providing the airflow 62-B at the rear of the cabinet 22,and the front two fans 126 substantially contribute to providing theairflow 62-A at the front of the cabinet 22 for higher velocity airflowat the front of the cabinet 22.

Furthermore, it should be understood that the data storage circuitrysubsystem 28 was described above as having a fan assembly 46 that isseparate and independent of fans for the power supply subsystem 24 andthe data storage subsystem 26 by way of example only. In otherarrangements, the data storage circuitry subsystem 28 shares the fanassembly 46 with the other subsystems 24, 26. In particular, thevertically oriented air stream 62 generated by the fan assembly 46 flowsthrough each subsystem 24, 26, 28 and eventually exhausts to a locationnear the top of the cabinet 22. This alleviates the need for the othersubsystems 24, 26 to have separate and independent fans and enables theother subsystems 24, 26 to leverage off of a single fan assembly 46 toreduce costs as well as to provide effective cooling in the verticaldirection within the rack mount cabinet 22.

Additionally, it should be understood that the fan assembly 46 wasdescribed above as being higher than the circuit boards 52, 54 to drawor pull air past the circuit boards 52, 54. In other arrangements, thefan assembly 46 is underneath the circuit boards 52, 54 and thus pushesair past the circuit boards 52, 54.

Furthermore, it should be understood that the data storage circuitrysubsystem 28 was described above as forming part of a rack mount datastorage system 20 by way of example only. In other arrangements, thedata storage circuitry subsystem 28 forms part of a different systemsuch as a network system, a general purpose computer system, specializedequipment, etc. Moreover, the rack mount cooling techniques can beapplied to other types of circuitry other than data storage circuitry(e.g., display equipment, networking equipment, mechanical equipment,fiber optic equipment, laser equipment, general purpose computerequipment, analog electronics, and the like), and such techniques areintended to belong to various embodiments of the invention.

1. A data storage subsystem for mounting within a rack mount cabinet,the data storage subsystem comprising: a housing configured to mount toa set of vertical rails of the rack mount cabinet; a set of circuitboards configured to install in a vertically aligned manner within thehousing to define a set of vertically oriented channels within a centralspace defined by the set of vertical rails of the rack mount cabinet;and a fan assembly configured to mount to the set of vertical rails in aposition above the housing to generate a vertical air stream through theset of vertically oriented channels and to exhaust the vertical airstream to an external location above the rack mount cabinet; wherein thehousing includes a card cage configured to hold the circuit boards in asubstantially parallel manner, and wherein the data storage subsystemfurther comprises: a backplane disposed within the card cage in asubstantially perpendicular manner to the set of circuit boards toprovide a set of high density connections to the set of circuit boards;wherein the set of circuit boards includes a set of front-installationcircuit boards which is configured to insert into the card cage througha front of the rack mount cabinet, and a set of rear-installationcircuit boards which is configured to insert into the card cage througha rear of the rack mount cabinet; and wherein the backplane includes: arigid planar member having a front side that faces toward the front ofthe rack mount cabinet and a rear side that faces toward the rear of therack mount cabinet, a set of front backplane connectors disposed on thefront side of the rigid planar member to connect with the set offront-installation circuit boards, and a set of rear backplaneconnectors disposed on the rear side of the rigid planar member toconnect with the set of rear-installation circuit boards.
 2. The datastorage subsystem of claim 1 wherein the set of front-installationcircuit boards is configured to perform data storage system operationson a set of disk drives on behalf of a set of external hosts, whereinthe set of rear-installation circuit boards is configured to operate asan interface between the set of front-installation circuit boards andthe set of external hosts, and wherein the data storage subsystemfurther comprises: a front door configured to reside adjacent thehousing at the front of the rack mount cabinet to operatively controluser access to the set of front-installation circuit boards when the setof front-installation circuit boards is inserted into the card cage, anda rear door configured to reside adjacent the housing at the rear of therack mount cabinet to operatively control user access to the set ofrear-installation circuit boards when the set of rear-installationcircuit boards is inserted into the card cage, the front and rear doorsbeing configured to (i) prevent air of the vertical air stream fromsubstantially escaping through the front and rear of the rack mountcabinet and (ii) deflect air of the vertical air stream through the setof vertically oriented channels defined by the set of circuit boards. 3.The data storage subsystem of claim 2 wherein the rigid planar member ofthe backplane is configured to divide the set of vertically orientedchannels into a set of front airways proximate to the front of the rackmount cabinet to carry a first portion of the vertical air stream and aset of rear airways proximate to the rear of the rack mount cabinet tocarry a second portion of the vertical air stream.
 4. The data storagesubsystem of claim 3 wherein the fan assembly is configured to provide,as the first portion of the vertical air stream, a first airflow throughthe set of front airways and a second airflow, as the second portion ofthe vertical air stream, through the set of rear airways; and whereinthe first airflow has a higher velocity than the second airflow.
 5. Thedata storage subsystem of claim 1 wherein the fan assembly includes: acarrier configured to mount to a set of top portions of the set ofvertical rails of the rack mount cabinet; and a set of fan subassembliessupported by the carrier, the set of fan subassemblies being configuredto exhaust the vertical air stream in a direction that is substantiallyparallel to the set of vertical rails and into the external locationabove the rack mount cabinet.
 6. The data storage subsystem of claim 5wherein each fan subassembly includes: multiple fans disposed in a row,that fan subassembly being configured to insert into the carrier in ahorizontal direction that is substantially perpendicular to the verticalair stream.
 7. The data storage subsystem of claim 6 wherein themultiple fans define a horizontal M×N array of fans where M is greateror equal to 2 and N is greater or equal to
 2. 8. The data storagesubsystem of claim 6 wherein each fan subassembly is configured tooperate independently of the other fan subassemblies to enable hotswapping of an individual fan subassembly while other fan subassembliesremain in operation.
 9. The data storage subsystem of claim 8 whereineach fan subassembly further includes: a status indicator to selectivelyindicate proper operation and improper operation of the multiple fans ofthat fan subassembly.
 10. A data storage subsystem for mounting within arack mount cabinet, the data storage subsystem comprising: a housingconfigured to mount to a set of vertical rails of the rack mountcabinet; a set of circuit boards configured to install within thehousing to define a set of channels within a central space defined bythe set of vertical rails of the rack mount cabinet; and a fan assemblyconfigured to generate an air stream through at least one of the set ofchannels to an external location above the rack mount cabinet; and abackplane assembly disposed in a substantially perpendicular manner tothe set of circuit boards to provide a set of high density connectionsto the set of circuit boards; wherein the set of circuit boards includesa set of front-installation circuit boards which is configured to insertthrough a front of the rack mount cabinet, and a set ofrear-installation circuit boards which is configured to insert through arear of the rack mount cabinet; and wherein the backplane assemblyincludes: a connection mechanism having a front side that faces towardthe front of the rack mount cabinet and a rear side that faces towardthe rear of the rack mount cabinet, a set of front backplane connectorsdisposed on the front side of the connection mechanism to connect withthe set of front-installation circuit boards, and a set of rearbackplane connectors disposed on the rear side of the connectionmechanism to connect with the set of rear-installation circuit boards.11. The data storage subsystem of claim 10 wherein the connectionmechanism of the backplane assembly includes: a rigid planar memberwhich defines the front side that faces toward the front of the rackmount cabinet and the rear side that faces toward the rear of the rackmount cabinet.
 12. The data storage subsystem of claim 11 wherein theset of front-installation circuit boards is configured to perform datastorage system operations on a set of disk drives on behalf of a set ofexternal hosts, wherein the set of rear-installation circuit boards isconfigured to operate as an interface between the set offront-installation circuit boards and the set of external hosts, andwherein the data storage subsystem further comprises: a front doorconfigured to reside adjacent the housing at the front of the rack mountcabinet to operatively control user access to the set offront-installation circuit boards when the set of front-installationcircuit boards is inserted through the front of the rack mount cabinet,and a rear door configured to reside adjacent the housing at the rear ofthe rack mount cabinet to operatively control user access to the set ofrear-installation circuit boards when the set of rear-installationcircuit boards is inserted through the rear of the rack mount cabinet,the front and rear doors being configured to (i) prevent air of the airstream from substantially escaping through the front and rear of therack mount cabinet and (ii) deflect air of the air stream through atleast one of the set of channels.
 13. A data storage subsystem formounting within a rack mount cabinet, the data storage subsystemcomprising: a housing configured to mount to a set of vertical rails ofthe rack mount cabinet; a set of circuit boards configured to install ina vertically aligned manner within the housing to define a set ofvertically oriented channels within a central space defined by the setof vertical rails of the rack mount cabinet; and a fan assemblyconfigured to mount to the set of vertical rails in a position above thehousing to generate a vertical air stream through the set of verticallyoriented channels and to exhaust the vertical air stream to an externallocation above the rack mount cabinet; wherein the housing includes acard cage configured to hold the circuit boards in a substantiallyparallel manner, and wherein the data storage subsystem furthercomprises: a backplane disposed within the card cage in a substantiallyperpendicular manner to the set of circuit boards to provide a set ofhigh density connections to the set of circuit boards; wherein the setof circuit boards includes a set of front-installation circuit boardswhich is configured to insert into the card cage through a front of therack mount cabinet, and a set of rear-installation circuit boards whichis configured to insert into the card cage through a rear of the rackmount cabinet; and wherein the backplane includes: a rigid planar memberhaving a front side that faces toward the front of the rack mountcabinet and a rear side that faces toward the rear of the rack mountcabinet, means for connecting with the set of front-installation circuitboards, and means for connecting with the set of rear-installationcircuit boards.